user
Suggest a data structure to store user data.

assistant
A hash table is an ideal data structure to store user data. Hash tables allow for efficient retrieval of user data, as they use a key-value pair system to store data. This means that a given key corresponds to a specific value, making it easy to look up a specific user's data when needed. Furthermore, hash tables are also suitable for large data sets, as they can grow and shrink dynamically and have a constant time complexity for insertion and removal of data.